1. Field of the Invention
The invention relates to atomized metal coating. In one of its aspects, the invention relates to a spray gun process to apply an atomized metallic coating to plastic parts evenly and without warpage.
2. Description of the Prior Art
Metallic spray guns have previously been used to spray a metallic coating onto metal parts. The metal coating was desired for various reasons. The metallic coating consisting of a more durable metal sprayed upon a part consisting of softer metal often increased the durability and life span of the coated metal part. A shiny metal coating was often placed upon a dull metal part to increase the aesthetic appearance of the metal part.
One spray gun which produced a metallic coating of good quality was a spray pistol manufactured by Ionarc Company under the trademark Arc Spray 200. The Arc Spray 200 uses maximum air pressure stream of 100 PSI and a wire feed rate of 24 pounds per hour for each 100 amps of current used to melt the wire at 220 volts.
In recent years a strong need for metallic coated plastic parts has arisen. Plastic parts are now used as a substitute for metal parts for a variety of uses.
Plastic parts are used in computers and electrical devices. Certain electrical devices are sensitive to radio frequencies, and such radio frequencies often interfere with the success of the electrical device. Plastic parts are unable to shield the electrical devices from radio frequency interference.
Plastic parts are also used in many devices which produce substantial amounts of heat. The plastic material, however, is not capable of conducting heat away from the certain hot spot.
To eliminate the above problems, plastic parts need a metallic coating. Plastic parts are now electroplated with silver. However, the electroplating process is expensive and time consuming.
Previous attempts to spray a metal coating onto plastic parts have been made but without success. The application of the metallic coating has so far been unsuccessful because the spray has given an uneven application to the plastic, the heat of metallic spray has caused warpage to the plastic part, or the application was not complete, leaving corners and crevices of the plastic parts exposed.